Power unit



v 13, .1946. E. A. ROCKWELL POWER ILINIT 3 Shee tS-Sheet l Original FiledNov. 8', 1938 IQNVENTOR am a Aug. 13, 1946. E. A. ROCKWELL POWER UNIT Original Filed Nov. 8, 1938- 5 Sheets-sheaf, 2

i r {@VNTQR I Patented Aug. 13, 1946 T @FFHQE 2,405,852 POWER UNIT Edward A. Rockwell,

Forest Hills, N. Y., assignor to The New Britain Machine Company, New

poration of Connecticut Britain, Conn a cor Original application November 8, 1938, Serial No.

' Divided and this application Decemher 1, 1939', ser a No. 307,116

My invention relates particularly to a power unitapplicable to systems for the application of power for. any desired purpose but also has especial application in connection with the operation of automotive accessories,

This'is a divisional application of my application upon Power system, Ser. No. 239,436; filed November 8, 1938.

The object of my invention is to provide a power unit for the application of power for any desired purpose, but it is especially useful in connection with the operation of automobiles and other automotive accessories. One of the objects of my invention is to provide a self-contained power unit which is capable of being mounted wherever desired uponan automobile or other automotive vehicle, inasmuch as the connections to the operating parts of the automotive structure are fully hydraulic, that is to say without the necessity of applying mechanical reaction members or devices between said unit and any 'access'oryto be operated thereby. A further important object is the application of the same for the operation of brakes, the same being constructed in such a manner that'the said brakes are moved into operative position manually initially, after which the powerirom said power unit is brought into action to apply the desired braking effect to the wheels, thus eliminating the necessity of utilizing the high pressurehydraulic power except in the actual braking effort to be applied. This enables, furthermore, the braking effort to be applied effectively, without requiring the movement of the foot pedal to substantially its entire" available range of movement,'as was previously required in other systems. Also, this avoids having to allow for lost-motion in lever and linkconnections. A further object is to carry out the operation in this way, although permitting the manual application of the braking effort in case of any failure of the application of power to the brakes. Still another object is to arrange the operating parts of the power unit in such close relation as to avoid lag in the relative 'movement'of the parts. This arrangement is such, furthermore, as to permit the placement of the power unit at practically any point on an automobile chassis, which is of importance due to the limited space available inautomobiles as now manufactured. It also enables the unit to be removed from danger of'contact with road obstructions. In view of the said unit being provided with connections which are fully hydraulic, furthermore, the installation can be carried out in a very 7 Claims. (01. -545 small fraction of the time that was required in thecase of previous systems having mechanically operating connections thereto. This enables, furthermore, the unit to be readily serviced by merely removing the unit and connecting a new power unit in its stead to the required tubular lines. The power unit is so constructed that it does not exert any thrust on the automotive parts on which it is mounted and will consequently retain its position when so mounted without danger of displacement or loosening, and even in the event of such loosening or displacement, will continue to function nevertheless. The whole structure and installation can, therefore, be applied to automobiles with a very small fraction of the cost hitherto necessary in power units used for the operation of automobile accessories.

Further objects of my invention will appear from the detailed description of the same hereinafter.

While my invention is capable of being carried out in many different ways, for the purpose of illustration I have shown certain embodiments of the same in the accompanying drawings, in which- Fig. 1 is a diagrammatic perspective view of an automobile chassis equipped with my invention, as adapted to be operated by a vacuum;

Fig. 2 is a longitudinal vertical section of the power unit shown in Fig. 1 showing the position at the initial application of hydraulic pressure;

Fig. 3 is an end elevation of a casting contained within the outer casing taken from the-left end f F Fig. 4 is a vertical section on line l-i of the same looking from the right towards the left of Fig. 2; and

Fig. 5is a vertical section of a modified form of my invention, in which compressed air is used instead of a vacuum, and showing diagrammatically the connections thereto.

Referring first to Figs. 1 to 4, I have shown an automobile chassis I' having front wheels 2 and rear wheels 3 mounted on a chassis 4 by means of springs 5 and 6, respectively, the same being connected to longitudinalframe members 7 and 8 having a cross-beam 9, as well as an internal combustion engine It having a' down-draft carbureter H leading to an engine manifold M a and having any other usual desired equipment. On the said chassis, accessible to the driver, there is a foot pedal l2 carried by a'p-ivot [3 on the chassis, which is connected by a link I4 tov an operating lever I5 tight on a shaft 16 which extendsinto casting 34b having serrations 340 on way 48 is normally closed by check-valve 53 therein forced against its seat in the master cylinder, which is adapted to move 7 a piston I3 therein which operates in a cylinder 23 having a hydraulic pressure fluid pipe con-.

nection 2|, which may be flexible. Th master cylinder is mounted in any desired. way, upon one of the frame members 9-of the chassis I. The said pipe 2| is connected by a fitting 22 to a casting or body member 23 forming a part of a power unit 24 which is mounted on the automobile chassis i in any desired manner and at any desired point thereon but, for example, by, means of U-shaped bolts 25 and 25 secured in place by nuts 2! on the frame member I. Within the 23 there is a passageway 28 which is connected by a fitting 29 to a tube 30 attached by a fitting 3I to a transverse passageway 32 which is located in a valve casing 33 screw-threaded to a cylindrical member 34, which in turn is screw-threaded also to the casting 23. Between the casing 33 and the cylinder 34 there is a rubber seal 34a which is U-shape in cross-section and is supported on one face thereof by a washer one face thereof, to permit the passage of liquid, the said washer 3411 being supported at its other side by a ring 34d. The liquid from the master cylinder thus conveyed by the tube 30 and the port 32 is received in a circular recess 35 in the valve casing 33, said recess having therein a serrated ring 35 having four serrations 31 thereon, said ring being supported within a U-shaped rubber seal 38 to provide a seal around a valve plunger 39, hereinafter described more in detail. On account of the serrations 31 the hydraulic fluid is allowed to pass from the recess 35 into a passageway in the casing 33 and thence through a fitting 4! to a tube 4 2, a fitting 42a, and a tiny capillary opening 42b to prevent the actuation of the atmospheric inlet and outlet valve, hereinafter described, before the brake shoes have been moved a into position, and thence to a pressure chamber 43 located in a casting 44 on the other end of the having an inner end 46 of reduced diameter through which there are four radial passageways 4'! connecting to a longitudinal passageway 48 to act as a passage for the escape of any accumulated air from the hydraulic fluid. The passageplug 43 having within .the sam a removable screw-threaded closure 50, upon the removal of which any accumulated air may be allowed to escape. The pressure chamber 45 thus permits manual pressure to be applied to a plunger 5| in the casting 44 in which it is sealed by an annular U-shaped rubber seal 52 held in place by a washer 53 and a snap-ring 54. The said plunger 5I is connected to a dished relief outlet valve or vacuum valve 55 in a vacuum chamber 55 in the casting 44, which is connected by passageways 56a and 55b to the exterior of said casting 44 and which is also connected by a longitudinal passageway 51 to a check-valve casing 58 having a y a spring 65. Within the check-valve casing 58 there is a longitudinal passageway BI communicating with lateral ports 62 which can be more or; less closed, as"desired, *by a screw-threaded ,lugi63 within the said passageway 6i and which means of a screwthe plug 6! and being of a star-shaped spring 53.

and passes through an opening power unit, which is closed by a screw-plug 45 shoe washer 9 I.

' located around the can be rotated by means of a squared extension 64 thereon fitting within a similar recess 65 in a rotatable adjusting member 66 carried within a screw-plug 6'! in the check-valve casing 58, said rotatable member 63 having a pointer 68 cooperating with a graduated scale on the outside of held outwardly by means The ports 52 lead to a circular passageway II! within a fitting II around the casing 58 and having a nipple I2 to which there is connected a flexible hose I3 by means of a clip I4. The hose I3 leads to the engine manifold IIa. A spacing member I5 is provided around the check-valve casing 58 and a flange i5 is provided on the screw-plug 45 to act as spacing members to hold in place an air filter casing 11 on the outside of said unit, having an air inlet opening I8 leading to a space I9 filled with horsehair, and also for holding in place an. end housing through which the plug 45 and the valve casing 53 extend. A gasket BI is located. between the end housing and the casting 44. The: air thus admitted to the chamber I9 passes; through a screw-plug 82 in the casting 44 and thence into a passageway 83 in the casting 44,v 84 in a rubber diaphragm 85 and finally into an air chamber 86,v on the opposite side of said diaphragm 85 from the location of the relief valve or vacuum valve 55. It will be noted that the said diaphragm 85 acts; as a valve seat for the valve 55. On the same side of the diaphragm 85 as the valve 55 there is a supporting ring 81a for limiting the movement of said diaphragm in one direction and to act as a support for an air inlet valve 81 when said valve 8'! is in closed position, against said diaphragm 85. There is also on the same side of the diaphragm 35 as the valve 81 a central ring 88, the outside diameter of which is slightly larger than the inside diameter of the ring 81a and on the opposite side of said diaphragm 85 there is a supporting ring 89, the ring 88 and 83 being held in place by a ferrule 33 and by a horse- The ferrule 93 is arranged to support one end of a spring 32, the other end of which passes through an extension 93 on which as well as a rubber diaphragm 94 and a ring 35, the same being held in place by a horseshoe-shaped Washer 95. Attached to the casting 44 there is a spacing member or ring 31 between the two diaphragms 85 and 34, the same being held in place by a plurality of screws 38, which latter also support a cylinder 93 having a plurality of holes I30 therein and acting as a support for one end of the spring .92. Said cylinder is located around the plunger 33, the latter being connected therein to a piston IIlI which is comprised of two end plates I02 and IE3 havinglocated between the same a leather ring I04 which has a right-angle cross-section so as to fit within the cylinder 39. Also, there is carried on the plunger 39, adjacent to the plate I53, a retainer shell I55 for holding in place a felt ring I06 which acts as a peripheral support for the leather ring I34. A washer I3! is provided for holding these rings in place on the plunger 33 and around said plunger there is furthermore provided a light helical spring I08, the other end of which seats against'a closure I03, mounted on the valve housing 33, for said cylinder 99, having openings I It to give access to th vacuum in which the cylinder 99 is submerged and surrounded. A cork packing III is plunger 39, held in place by a shell II2 thereon. When the pressure in the pistons pressure chamber .43, in he m nne .h inaiter described, causes the plunger 39 to be moved t9 the right, in Fig. 2, the said plunger 39 cuts eff access of the pressure fluid from the tube to the interior of the cylinder also that further movement of the plunger 39 to the right forces the trapped liquid in the cylinder 34 out thml h a port H3 and-thence through a fitting Hit into a tu e 5 whi h s th o d y a i e sy tem H6 to fourewheel cylinders I It, all of which are constructed alike and each of which wheels for operating, res

carries two pistcns H8 and H9 spectively, brake shoes I 2t andIZI, which in this way apply the brakes to wheeldrums I22 located on the wheels 2 and 3, In completing the power unit there is fastened onto one end of the unit a cover I23 by means of screws I24 on the casting 23 and a ring I25 is spun onto flan ed edges of the cover I23 and the housing 6.8, so as to make a tight joint, thus submerging" all the parts within'same in a vacuum. For oiling purposes there is an inlet fitting IZiia closed by a plug I25b and which is connected by a pipe I25c'to the interior of the cylinder 95. 1

In the modificaticn of my invention, as shown in Fig. 5, the construction of the apparatus is the same as in the preceding figures except in the following respects: In this instance, instead of the source of vacuum there is provided a source of compressed air. Furthermore, the housing Bil and cover I23 are made strong enough to withstand whatever compressed air' pressures are used. Also, in this instance the apertures II Ii are omitted and an adequate breather tube I26 is connected from the tight closure We to the space I9. Furthermore, there is provided a source of compressed air I 2? connected by a clip I28 to a nipple I 29 having an annular passageway I 39 through which passes a screw pl g I3I having ports I32 leading to a ball check-valve I seated by a spring I34 so as to provide a body of compressed air within the housing 89 and cover I23. he compressed air thus supplied enters the valve structure through a port I35 in a spacing member I36 between diaphragms I3? and I36 which are constructed like the diaphragms 85 and 94. The exhaust air in this instance, when escaping from the valve 55, passes out through a passageway I39 in a casting I All, which is in other respects constructed like the casting 44, so that said air reaches the space 19 in communication with the outer air. Also ports 555a and 561) are omitted.

In the operation of my invention, referring first to Figs. 1 to 4, the engine II) being in operation and the vacuum being thus available through the pipe it, the same is conveyed to the power unit 24 as to submerge the parts therein within the same by way of the passageway 57, chamber 55, passageways a and 53b, to the inside of the housing as and cover I23. Also, the vacuum will extend from beneath the valve 55, which has no force seating it, through the ferrule 99 to the left face of the piston IfiI. When the pedal I2 is pressed downwardly to the extent desired, by the foot, the lever arm I8 within the master cylinder ll moves the piston is to force the hydraulic fluid in the pipe 2I into the power unit 24 and through the pipe 36 around the right-hand end of the plunger 29 and thence by the pipe H5 to the wheel brake cylinders II? so as to move the I I8 and I I9 and thereby move the brakeshoes I26 and I2I up to the point of contact with the brake drums I22. Up to this point the spring will remain substantially fully extended and the valve 55 will remain lightly in contact with the diaphragm ,85 as shownin Fig. 2 and the atmospheric inlet valve 87 will have remained closed due to the atmospheric air pressure forcing the seating of the latter on the diaphragm on the other side of which there is a vacuum, which seating remains tight due to the slight flexing of the diaphragm 85, as shown by the clearance between the plate 528 and the diaphragm B5 in Fig. 2 of the drawings. When further pressure, however, is exerted from the foot pedal I2 the pressure, which up to this point is received by the tube .42 and the pressure chamber 43 will have been insufiicient to move the diaphragm .85 to unseat the atmospheric inlet valve 81. will now push the valve. 87 or? its seat in opposition to the force of the spring 92, as the diaphragm .85 will then be flexed further to the right and the ferrule 953, 93 will also be moved to the right, thus simultaneously closing by tightly seating the valve 55 and moving the plunger 39 to the right in Fig. 2 by the force of the incoming air acting on the piston I-IlI, so as to seal the chamber within the cylinder 34 by reason of the seal 34a. The said piston 39 is, therefore, now moved initially due to the manual pressure from the liquid in the tube 42 but so as to in any event permit the manual application of the manual pressure on the brakes through the'pipe 3!), cylinder 34 and pipe I It in case there should be any failure of the power from the operation of the power unit. However, in the normal operation of the apparatus at this point, due to the seating of thevalve 55 and the unseating of the valve 87, the pressure of the atmospheric air entering through the passage way 18 and passageways 83 and $25 will pass through the ferrule 93 and the openings Ifli! to the face of the piston IllI so as to force the same to the right in Fig. 2, in view of the vacuum which is present on the other side of said piston, and, owing to the Very large diameter of the piston IEiI as compared to the diameter of the plunger 39, the very low manual force applied. as, for example, 50 to 400 lbs. per square inch, will be supplanted by a pressure up to but not exceeding 120!) lbs. per square inch in the tube H5 leading to the brake cylinders Hi. This maximum pressure to be obtained can be determined by the adjustment of the rotatable vacuum adjuster 56, and if, due to wear in the automobile, the maximum obtained is less than said maximum, the vacuum can be adjusted again by the rotatable adjuster 66 to provide a more eifective vacuum due to the changed tension in the spring 5%]; It will be noted, also, that the diaphragm supporting plates 88 and 95 and the peripheral supports of said diaphragms are, respectively, of the same size so that the effective areas of each diaphragm, that is to say the portion subjected to the differential between the two pressures on opposite sides thereof, is approximately the same as in the other diaphragm, to prevent sudden changes of movement. In this way a very power ful force is brought to bear upon the brake-shoes I28 and I2I according to the degree of the low manual pressure exerted. However, very little brake fluid will have been used or needed to be brought into motion to bring about the braking action, as the brake-shoes will have already been brought previously into position before the braking action by the manual force applied to the brake-shoes. Furthermore, it will be seen that this is accomplished by a very small degree of movement of the foot pedal as very little motion is required to bringthe brake shoes into operative position and substantially all ofthe subsequent effort is merely the exertion of the manual pressure with extremely little movement of the hydraulic fluid leading to the brake-shoes. In other words, the great disadvantage of previous hydraulic systems of requiring the foot to move through an extensive range with consequent danger of ineffectiveness, especially when used with boosters, is obviated, Upon the release of the pressure from the foot pedal I2 the spring 92 extends to close the valve 87 and the valve 55 opens so that air from within the left end of the cylinder 99 is exhausted, due to the vacuum in the pipe 33, and therefore the plunger 39 moves to the left, in Fig. 2, until the seal 34a is uncovered, thereby permitting the escape of any possible excess of the liquid which has been trapped beyond the end of the plunger 39 and releasing the brakes, so that the parts for operating the brakes are again in position for action whenever the brakes are to be applied, as previously described.

The operation of the modification shown in Fig. 5 is substantially the same as the form of my invention in the preceding figures except in this instance air pressure take the place of the atmospheric pressure on the left face of the piston illl, the other face of said piston being in communication with the outer air through the breather tube i26. In this instance, after the brake shoes have been moved into position initially by the hydraulic fluid through the pipes 30 and H5 the further pressure of the same acting on the plunger 5! tightly closes the valve 55 and causes the valve 81 to open because the diaphragm 85 is then further bowed to the right and the latter pushed off its seat by the ferrule 90, 93, thu admitting compressed air through said ferrule to the left face of the piston I01 which causes the latter to move to the right. The plunger 39 is then moved to the right, cutting off the communication between the pipe 30 and the passageway in the cylindrical member 34 and applying the high pressure in the liquid trapped therein to the brake shoes I20, IE! on the four wheel brakes, depending upon the amount of the modulated pressure applied by the foot to the pedal 12. Upon the release of the foot pressure in the off-modulation the braking efifect can be released as much as desired until finally upon the release of all foot pressure the parts are restored to their initial positions.

While I have described my invention above in detail I wish it to be understood that many changes may be made therein without departing from the spirit of the ame.

I claim:

1. A power unit comprising a valve for controlling the access of a pressure different from the atmosphere, a valve for controlling access of atmospheric air pres-sure, a hydraulic pressure connection leading to the outside of the power unit, including a plunger, for, operating said valves and which is subject to the reaction from said hydraulic pressure applied for seating one of said valves while unseating the other valve,

a movable wall normally submerged in one of said pressures, adapted to be moved by a difference of said pressures according to the position of said valves for performing work, means, including a hydraulic plunger, connected to the movable wall for providing and delivering from the power unit hydraulically an increased pressure, and an enclosure for the power unit, said hydraulic pressure connection including a body member with an inlet opening inserted in the enclosure and a conduit in the enclosure leading to said plunger and connected to said opening constituting thereby the hydraulic pressure connection.

2 A power unit comprising a valve for control ling the access of a pressure different from the atmosphere, a valve for controlling access of atmospheric air pressure, a hydraulic pressure connection leading to the outside of the power unit, including a plunger, for operating said valves and which is subject to the reaction from said hydraulic pressure applied for sea ing one of said valves while unseating the other valve, a movable wall normally submerged in one of said pressures, adapted to be moved by a difference of said pressures according to the position or" said valves for performing work, means, including a hydraulic plunger, connected to the movable wall for providing and delivering from the power unit hydraulically an increased pressure, a cylinder in which the movable wall reciprocates. having a cylinder head, a ring for supporting elements of said valves, and means for supporting said ring from said cylinder head.

3. A power unit comprising a valve for controlling the access of a pressure difierent from the atmosphere, a valve for controlling access or" atmospheric air pressure, a hydraulic pressure connection leading to the outside of the power unit, including a plunger, for operating said valves and which is subject to the reaction from said hydraulic pressure applied for seating one of said valve while unseating the other valve, a movable wall normally submerged in one of said pressures, adapted to be moved by a difference of said pressures according to the position of said valves for performing work, means, including a hydraulic plunger, connected to the movable wall for providing and delivering from the power unit hydraulically an increased pressure, a cylinder in which the movable wall reciprocates, having a cylinder head, a ring for supporting elements of said valves, and means for supporting said ring from said cylinder head, said elements comprising two diaphragms between which said ring is located and said ring having a passageway for the access of said atmospheric air pressure.

4. A power unit comprising a valve for controlling the access of a pressur different from the atmosphere, a valve for controlling access of atmospheric air pressure, a hydraulic pressure connection leading to the outside of the power unit, including a plunger, for operating said valves and which is subject to the reaction from said hydraulic pressure applied for seating one of said valves while unseating the other valve, a movable wall normally submerged in one of said pressures, adapted to he moved by a difference of said pressures according to the position of said valves for performing work, means, including a hydraulic plunger, connected to the movable wall for providing and delivering from the power unit hydraulically an increased pressure, a cylinder in which the movable wall reciprocates having a Cylinder ad, a ring for supporting elements of said valves, means for supporting said ring from said cylinder head, said elements comprising two diaphragms between which said ring is located and said ring having a passageway for the access of said atmospheric air pressure, and a housing for said first mentioned plunger fastened to said ring and cylinder head.

5. A power unit for intensifying and modulating hydraulic pressure, to be interposed as a unit in the hydraulic line between a master cylinder and an hydraulic motive means in a system of the character indicated, said power unit comprising a fluid-tight chamber casing, a cylinder mounted in said chamber casing and spaced circumferentially therefrom, a piston in said cylinder, passage means from said chamber casing to at least one side of said piston, a fluid pressure connection to said casing, valve means for controlling the connection between said one side of said piston in said cylinder and said chamber casing, an atmospheric connection, valve means for controlling the communication between said atmospheric connection and said one side of said piston, hydraulically actuated means for ocntrolling said valve means, an hydraulic cylinder, low pressure hydraulic connection means to said hydraulic cylinder and to said hydraulically actuated means, means for cutting 01? communication between said low pressure hydraulic connection means and said hydraulic cylinder and for thereafter generating high hydraulic pressure in said hydraulic cylinder while said hydraulically actuated means remains connected to said low pressure connection means for controlling said valve means by low hydraulic pressure, said means for generating high hydraulic pressure in said hydraulic cylinder including hydraulic piston means connected for operation by said first mentioned piston, high pressure hydraulic connection means to said hydraulic cylinder, all of the aforesaid power unit parts being assembled as an integral unit for unit handling and installation, and said fluid pressure connection, atmospheric connection, low pressure hydraulic connection means, and high pressure hydraulic connection means constituting the sole essential operative connections to said power unit.

6. A power unit for intensifying and modulating hydraulic pressure, to be interposed as a unit in the hydraulic line between a master cylinder and an hydraulic motive means in a system of the character indicated, said power unit compris ing a fluid-tight vacuum chamber casing, a cylinder mounted in said vacuum chamber and spaced circumierentially therefrom, a piston in said cylinder normally open at opposite sides to and subjected to the pressure in said vacuum chamber, a vacuum connection to said vacuum chamber casing, valve means for controlling the connection between one side of said piston and said vacuum chamber, an atmospheric connection to said one side of said piston, valve means for controlling communication between said atmospheric connection and said one side of said piston, hydraulically actuated means for controlling said valve means, an hydraulic cylinder secured to said vacuum chamber casing, low pressure hydraulic connection means to said hydraulic cylinder and to said hydraulically actuated means, means for cutting ofi communication between said low pressure 7 in said hydraulic cylinder including hydraulic piston means connected for operation by said first mentioned piston, high pressure hydraulic connection means to said hydraulic cylinder, all of the aforesaid power unit parts being assembled as an integral unit for unit handling and installation, and said vacuum connection, atmospheric connection, low pressure hydraulic connection means and high pressure hydraulic connection means constituting the sole essential operative connections to said power unit.

, 7. A power unit for intensifying and modulating hydraulic pressure, to be interposed as a unit in the hydraulic line between a master cylinder and an hydraulic motive means in a system of the character indicated, said power unit comprising a generally cylindrical unit including a fluid pressure actuated means, a valve casing at one axial end of the unit, an hydraulic cylinder at the other axial end of the unit, said fluid pressure actuated means being located between said hydraulic cylinder and said valve casing, fluid pressure connection means to said unit, valve means in said valve casing to control the flow of pressure fluid to and from said fluid pressure actuated means, hydraulically actuated means for controlling said valve means, low pressure hydraulic connection means to said hydraulic cylinder and to said hydraulically actuated means, high pressure bydraulic connection means to said hydraulic cylinder, means for cutting off communication between said low pressure hydraulic connection means andsaid hydraulic cylinder and for thereafter generating high hydraulic pressure in said hydraulic cylinder while said hydraulically actuated means remains connected to said low pressure hydraulic connection means for controlling said valve means by low hydraulic pressure, said means for generating high hydraulic pressur in said hydraulic cylinder including hydraulic piston means connected for operation by said fluid pressure actuated means, said fluid pressure actuated means, hydraulic cylinder, piston means, valve casing and valve means, and said hydraulically actuated means being assembled as an integral unit for unit handling and installation, and said fluid pressure connection means, said low pressure and said high pressure hydraulic connection means constituting the sole essential operative connections to said power unit.

EDWARD A. ROCKWELL. 

